1. Field of the Invention
This invention relates to a loading dock and a maintenance prop for a dock leveler. A dock leveler is used to bridge the distance between the floor of a building and the bed of a truck. A typical dock leveler has a stationary frame, a deck hinged at the rear to the frame, and a deck extension or lip hinged to the front of the deck. A dock leveler may have various means to raise the deck and extend the lip, including hydraulic, electric or mechanical. Usually the operating means is located under the deck which must be raised to allow access for periodic maintenance. To ensure the safety of the maintenance workers, a maintenance prop is usually provided to support the deck in the raised position.
2. Prior Art
The maintenance prop is usually a bar or tube which is placed with the lower end resting on the frame of the dock leveler or on the floor of the pit, and the upper end under the deck or the lip. The prop may be separate from the dock leveler, attached by a chain to prevent misplacing it, or attached by a hinge to the deck or the frame so that it may be rotated between a stored and an engaged position. The primary purpose of the maintenance prop is to ensure that the deck is not accidentally lowered while someone is working under it. It may also be desirable to have a means of locking the prop in the engaged position to prevent the leveler from being used until maintenance has been completed.
Some dock levelers have a maintenance prop which supports the lip in the extended position. An example which supports the lip is illustrated in U.S. Pat. No. 4,376,319. Others support only the deck and allow the lip to be extended or retracted in the maintenance position. Some dock levelers have an independent support for the lip. The lip support shown in U.S. Pat. No. 4,376,319 is manually engaged and automatically retracts when the weight of the lip is removed from it. Unless the operator inserts the safety pin in the lip support bar, it will automatic disengage if the lip is momentarily raised from the maintenance prop.
Another example of a maintenance strut that supports the lip is found in U.S. Pat. No. 5,546,623. This device comprises a removable strut that is positioned by a base member and a hole in the lip. The strut protrudes through the lip and is pinned in place, top and bottom. A support block, mounted on the strut, rests under the lip and positions the deck at the proper height for working under the deck.